Question

Difficulty: EasyPositive and Negative Number Properties

If xx is a negative integer and yy is a positive integer, what is the value of xyyxx+y+100\frac{|x - y| - |y - x|}{x + y + 100}?

Answer: 0

Answer

0
Given x<0x < 0 and y>0y > 0, the quantity xyx - y is strictly negative, which means xy=(xy)=yx|x - y| = -(x - y) = y - x. The quantity yxy - x is strictly positive, so yx=yx|y - x| = y - x. Thus, the numerator simplifies to (yx)(yx)=0(y - x) - (y - x) = 0. Dividing zero by any non-zero denominator yields 00.

Step-by-Step Solution

1
Determine the signs of the terms inside the absolute value functions
Since x<0x < 0 and y>0y > 0, xy<0x - y < 0 and yx>0y - x > 0.
Subtracting a positive number from a negative number yields a negative value, while subtracting a negative number from a positive number yields a positive value.
2
Simplify the absolute value expressions
xy=yx|x - y| = y - x and yx=yx|y - x| = y - x.
The absolute value of a negative number is its negation, and the absolute value of a positive number is the number itself.
3
Compute the difference in the numerator
xyyx=(yx)(yx)=0|x - y| - |y - x| = (y - x) - (y - x) = 0.
Subtracting an algebraic expression from an identical expression results in zero.
4
Evaluate the entire fraction
0x+y+100=0\frac{0}{x + y + 100} = 0.
Zero divided by any non-zero real number is zero.

Key Concept

Positive and Negative Number Properties with Absolute Value
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